cmd/dlv: address comments - made the --connect unhidden

Documentation/usage/dlv_dap.md

@@ -17,13 +17,18 @@ The server does not yet accept multiple client connections (--accept-multiclient
 While --continue is not supported, stopOnEntry launch/attach attribute can be used to control if
 execution is resumed at the start of the debug session.
 
+The --connect flag is a special flag that makes the server operate in reverse mode.
+In this mode, Delve connects to a DAP client listening on host:port,
+instead of listening for connections.
+
 ```
 dlv dap
 ```
 
 ### Options
 
 ```
+      --connect string   host:port of the DAP client when running in reverse mode.
 ```
 
 ### Options inherited from parent commands

cmd/dlv/cmds/commands.go

@@ -61,9 +61,9 @@ var (
 	// disableASLR is used to disable ASLR
 	disableASLR bool
 
-	// dapConnect is dap subcommand's hidden flag that sets the rendezvous point address.
+	// dapConnect is dap subcommand's flag that specifies the address of a DAP client.
 	// If it is specified, the dap server operates in reverse mode and
-	// communicate only through the proxy dap server at the rendezvous point.
+	// and dials into the client waiting there.
 	dapConnect string
 
 	// backend selection
@@ -190,11 +190,14 @@ to be launched or process to be attached to. The following modes are supported:
 - attach + local (attaches to a running process, like 'dlv attach')
 The server does not yet accept multiple client connections (--accept-multiclient).
 While --continue is not supported, stopOnEntry launch/attach attribute can be used to control if
-execution is resumed at the start of the debug session.`,
+execution is resumed at the start of the debug session.
+
+The --connect flag is a special flag that makes the server operate in reverse mode.
+In this mode, Delve connects to a DAP client listening on host:port,
+instead of listening for connections.`,
 		Run: dapCmd,
 	}
-	dapCommand.Flags().StringVar(&dapConnect, "connect", "", "host:port of the proxy DAP server. If set, the command starts a DAP server in reverse mode")
-	dapCommand.Flags().MarkHidden("connect")
+	dapCommand.Flags().StringVar(&dapConnect, "connect", "", "host:port of the DAP client when running in reverse mode.")
 
 	rootCommand.AddCommand(dapCommand)
 

service/dap/server.go

@@ -89,19 +89,15 @@ import (
 // when halt is issued while stopping. At that point these goroutines
 // wrap-up and exit.
 //
-// The DAP server set up using NewReverseDAPServer is a special
-// DAP server, that is bound to a single net.Conn. Once the connection
-// is closed, the server is stopped. Its Run is never called, but
-// the NewReverseDAPServer immediately starts serveDAPCodec on the
-// net.Conn.
+// The DAP server set up using NewReverseServer is a special DAP server,
+// that is bound to a single net.Conn. Once the connection is closed,
+// the server stops.
 type Server struct {
 	// config is all the information necessary to start the debugger and server.
 	config *service.Config
 	// listener is used to accept the client connection.
+	// In reverse mode, this is nil.
 	listener net.Listener
-	// inReverseMode is true if this server operates in reverse mode
-	// where listener is nil.
-	inReverseMode bool
 	// stopTriggered is closed when the server is Stop()-ed.
 	stopTriggered chan struct{}
 	// reader is used to read requests from the connection.
@@ -219,11 +215,13 @@ func NewReverseServer(config *service.Config, conn net.Conn) *Server {
 
 func newServer(config *service.Config, conn net.Conn, inReverseMode bool) *Server {
 	logger := logflags.DAPLogger()
-	if !inReverseMode {
+	if config.Listener != nil {
 		logflags.WriteDAPListeningMessage(config.Listener.Addr().String())
 		logger.Debug("DAP server pid = ", os.Getpid())
-	} else {
+	} else if conn != nil {
 		logger.Debug("Reverse DAP server pid = ", os.Getpid())
+	} else {
+		logger.Fatal("Cannot set up a DAP server without network configuration")
 	}
 
 	return &Server{
@@ -235,7 +233,6 @@ func newServer(config *service.Config, conn net.Conn, inReverseMode bool) *Serve
 		variableHandles:   newVariablesHandlesMap(),
 		args:              defaultArgs,
 		exceptionErr:      nil,
-		inReverseMode:     inReverseMode,
 		conn:              conn,
 	}
 }
@@ -294,7 +291,7 @@ func (s *Server) Stop() {
 	s.log.Debug("DAP server stopping...")
 	close(s.stopTriggered)
 
-	if !s.inReverseMode {
+	if s.listener != nil {
 		_ = s.listener.Close()
 	}
 
@@ -357,7 +354,7 @@ func (s *Server) triggerServerStop() {
 // TODO(polina): allow new client connections for new debug sessions,
 // so the editor needs to launch delve only once?
 func (s *Server) Run() {
-	if s.inReverseMode {
+	if s.listener == nil {
 		go s.serveDAPCodec()
 		return
 	}